Name: ________________________________
Per: _____
Date: ____________
WS How Atoms Differ
Answer the questions below.
1. What is the atomic number of an atom? _______________________________________________
2. What is the mass number of an atom? _________________________________________________
________________________________________________________________________________
3. How do you find the mass number of an atom? __________________________________________
4. Every neutral atom has the same number of ________________ and _______________.
5. How do you find how many neutrons if you know the mass number and atomic number?
________________________________________________________________________________
6. Which subatomic particles are in the nucleus? ___________________________________________
For each statement below, write true or false.
__________ 7. The number of neutrons is arranged by increasing atomic number.
__________ 8. The periodic table is arranged by increasing atomic number.
__________ 9. Atomic number is equal to the number of electrons in an atom.
__________ 10. The number of protons in an atom identifies it as an atom of a particular element.
__________ 11. Most atoms have either a positive or a negative charge.
Answer the following questions.
12. Lead has an atomic number of 82. How many protons and electrons does it have? _____p+, _____e13. Oxygen has 8 electrons. How many protons does oxygen have? _________
14. Zinc has 30 protons. What is its atomic number? _______
15. Astatine has 85 protons. What is its atomic number? _______
16. Rutherfordium has an atomic number of 104. How many protons and electrons does it have?
______ p+, ______ e-.
17. Polonium has an atomic number of 84. How many protons and electrons does it have?
______ p+, ______ e-.
18. Neobelium has an atomic number of 102. How many protons and electrons does it have?
______ p+, ______ e-.
Determine the number of protons, electrons, and neutrons for each isotope described below.
19. An isotope has atomic number 19 and mass number 39. _____ p+, _____ e-, _____ n
20. An isotope has 14 electrons and a mass number of 28. _____ p+, _____ n
21. An isotope has 21 neutrons, and a mass number of 40. _____ p+, _____ e22. An isotope has an atomic number of 51 and a mass number of 123. _____ p+, _____ e-, _____ n
Answer the following question.
23. a) Which of the isotopes in problems 13 – 16 are isotopes of the same element?
_______________________________________________________________________________
b) Identify the element. ____________________
Write each isotope below in symbolic notation. Use the periodic table to determine the atomic
number of each isotope.
24. Neon-22
____________
25. Helium-4 ____________
26. Cesium-133
______________
27. Uranium-234
______________
28. Complete the chart below using a periodic table.
Atomic
Symbol
Mass
Number
Atomic
Number
108
# of
Protons
# of
Neutrons
19
21
Name of Isotope
47
28
127
# of
Electrons
31
I
53
carbon-14
18
137
56
22
55
Fe
26
29
36
lead-206
Circle the letter of the choice that best completes the statement.
28. The mass of an electron is
A. smaller than the mass of a proton.
B. smaller than the mass of a neutron.
C. a tiny fraction of the mass of an atom.
D. all of the above.
29. One atomic mass unit is
A. 1/12 the mass of a carbon-12 atom.
B. 1/16 the mass of an oxygen-16 atom.
C. Exactly the mass of one proton.
D. Approximately the mass of one proton plus one neutron.
30. The atomic mass of an atom is usually not a whole number because it accounts for
A. only the relative abundance of an atom’s isotopes.
B. only the mass of each of the atom’s isotopes.
C. the mass of the atom’s electrons.
D. both the relative abundance and the mass of each of the atom’s isotopes.
Use a periodic table to answer the following questions.
31. What is the chemical symbol for osmium?
__________
32. What is the atomic number for osmium?
__________
33. How many protons and electrons does an osmium atom have? _______p+, ______e34. What is the atomic mass of osmium?
__________________
35. What units is the atomic mass reported in?
______________________
36. Osmium has 6 isotopes with mass numbers of 184, 187, 188, 189, 190, and 192. Considering the
average atomic mass reported on the periodic table, which isotope is most abundant?
_____________________________
37. What is the chemical symbol for copper?
___________
38. What is the atomic number for copper?
___________
39. How many protons and electrons does an atom of copper have? ________ p+, _______ e40. What is the atomic mass of copper?
_________________
41. Copper has two isotopes with mass numbers of 63 and 65. Considering copper’s atomic mass,
which isotope is the most abundant?
_________________
42. If an element only had one isotope, would its atomic mass be a whole number? ________
Explain. _________________________________________________________________________
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